Sine-cosine to magnitude-phase angle converter

ABSTRACT

An analogue device for converting two voltages (AC or DC) each proportional to quadrature components E sin phi and E cos phi to two voltages, one proportional to E and one proportional to the phase angle phi .

United States Patent Inventor William B. Goggins, Jr.

Winchester, Mass.

Feb. 3, 1969 May 4, 1971 The United States of America as represented bythe Secretary of the Air Force Appl. No. Filed Patented AssigneeSlNE-COSINE TO MAGNlTUDE-PHASE ANGLE CONVERTER [56] References CitedUNITED STATES PATENTS 2,429,636 10/ 1947 McCoy 328/ 1 34 2,635,2264/1953 Harris 328/155X 2,860,306 1 1/ 1958 Towner 328/166X 3,012,20012/1961 l-lurvitz 328/134 3,042,871 7/1962 Bergman 328/ 133 3,368,0362/1968 Carter et a1. 178/67 3,390,343 6/1968 Carter 329/146 3,422,362l/l969 West 328/134 3,464,016 8/ 1969 Kerwin et a1 328/133X PrimaryExaminer-Donald D. Forrer Assistant Examiner-R. C. WoodbridgeAttorneys-Harry A. Herbert, Jr. and George Fine ABSTRACT: An analoguedevice for converting two voltages (AC or DC) each proportional toquadrature components E sin (I) and E cos 1 to two voltages, oneproportional to E and one proportional to the phase angle D.

SINE-COSINE T MAGNITUDE-PIIASE ANGLE CONVERTER BACKGROUND OF THEINVENTION In the art of analogue computers, fire control acquisition andtracking systems, and synthetic aperture radars, there has existed theproblem of rapid conversion from sine and cosine representation of avector or phasor to the magnitude-phase angle representation of aphasor. There exists a prior arrangement for modifying two analoguevoltages, particularly if they are vector components. The modificationto the analogue quantity is in the form of applying an identical factorto both electrical voltages representing the analogue quantities. Theresult produced by the arrangement is that both analogue quantities aremultiplied by one and the same factor. However, there are limitations inthe prior art. In the present invention, conversion from sine and cosinerepresentation to magnitude-phase angle is done directly and entirelyelectronically without the use of resolvers. Incorporation of a linear360 phase detector makes this possible. By using a high referencefrequency, the conversion can be accomplished as rapidly as necessary.

SUMMARY OF THE INVENTION There is provided an analogue device forconverting two voltages, each proportional to quadrature components Esin D and E cos I to two voltages, one proportional to E and oneproportional to the phase angle 1 Itis in a way an inverse resolver. Oneof the voltages is multiplied by a first reference signal having anyconvenient frequency and the other voltage is multiplied by a secondsignal phase shifted a predetermined magnitude from the first signal.The resulting signals are sinusoidal waveforms at amplitude E and at afrequency w,,,. The resulting signals are added to provide a phasorgiven by E cos (m -4%). The magnitude E is determined by passing thesignal through a linear detector, and the phase angle b, is detenninedby passing E (w,,at+ through a limiter and then passed through a phasedetector which simultaneously receives the aforesaid reference signal.

An object of the present invention is to provide an analogue device forconverting two voltages, each proportional to quadrature components Esin (I and E cos (I one proportional to E and one proportional to thephase angle I Another object of the present invention is to provide ananalogue device for the conversion from sine and cosine representationto magnitude-phase angle representation.

The various features of novelty which characterize this invention arepointed out with particularlity' in the claims annex'ed to and fonningpart of the specification. For a better understanding of the invention,however, its advantages and specific objects obtained with its use,reference should be had to the accompanying single drawing anddescriptive matter in which is illustrated and described and preferredembodiment of the invention.

DESCRIPTION OF THE DRAWING The single drawing of the invention shows inblock diagram a sine-cosine to'magnitude-phase converter.

tion, there is shown multipliers l2 and 13. Multiplier 12 receives avoltage signal, E sin D by way of input terminal 10 and multiplier 13receives a voltage signal, E cos 1 by way of input terminal 11. The twoinput voltage signals may be bipolars or voltages, either DC or AC.Multiplier 12 simultaneously receives a second input by way of referencesource 14 which may be a signal generator providing a sinusoidalwaveform with a preselected convenient frequency. Multiplier 12multiplies voltage E sin l by a sinusoidal waveform denoted as sin m Thesignal, sin m from reference source 14 i2 received by 9 0 phase shifter16 to provlde a signal, cos m for application to multiplier 13.Multiplier 13 multiplies the voltage E cos b, by cos m The resultingsignals are sinusoidal waveforms at an amplitude E and at a frequency wThe two signals are added together in summer 17. Summer 17 may be anyconventional summing network or amplifier which will respond properly tothe frequency m The result of the summation is the phasor given by E cos(m,,,+,). The magnitude E is determined by passing the signal throughlinear detector 18. Any conventional linear detector may be used. Theoutput of linear detector 18 is applied to magnitude indicator 19 whichmay be a voltmeter or other suitable measuring device.

The phase angle I is determined by first passing E cos (0),, 1%) throughlimiter 20 in order to remove any amplitude information. Anyconventional limiter which is phase stable over the expected dynamicrange of E may be used. The phase angle I is then determined in linearphase detector 21 by comparing the output of limiter 20 with thereference frequency sin m Any conventional 360 phase degree detector maybe used. The output of phase detector 21 is then a signal representativeof the phase angle. Thus, in accordance with the present invention,there is determined E and D Although the invention has been describedwith reference to a particular embodiment, it will be understood tothose skilled in the art that the invention is capable of a variety ofalternative embodiments within the spirit and scope of the appendedclaims.

lclaim:

l. A sine-cosine to magnitude-phase converter comprising a first andsecond multiplier, said first multiplier receiving a voltage input, Esin I and said second multiplier receiving a voltage input, E cos 4 areference source providing a sinusoidal signal, E sin 1 of preselectedfrequency, also serving as an input to said first multiplier, means toshift said signal from said reference source prior to being received bysaid second multiplier, said multiplier providing resulting signals ofsinusoidal waveforms at an amplitude E and at a frequency m means to addthe resultant signals from said multipliers to provide a resultantphasor given by E cos (w HD representative of magnitude and phase, andmeans to detect linearly the absolute value of said resultant phasor Ecos (w l- D 2 A converter as described in claim 1 further includingmeans to measure the magnitude of the output from said linear detector.

3. A converter as described in claim 2 further including a means tolimit the amplitude of said resultant phasor, E cos (co q and means tocompare the phase of the signal output from said amplitude limiter tosaid signal from said reference source.

4. A converter as described in claim 3 wherein said means to comparephase consists of a 360 phase detector.

1. A sine-cosine to magnitude-phase converter comprising a first andsecond multiplier, said first multiplier receiving a voltage input, Esin phi , and said second multiplier receiving a voltage input, E cosphi , a reference source providing a sinusoidal signal, E sin phi c, ofpreselected frequency, also serving as an input to said firstmultiplier, means to shift said signal from said reference source 90*prior to being received by said second multiplier, said multiplierproviding resulting signals of sinusoidal waveforms at an amplitude Eand at a frequency omega m, means to add the resultant signals from saidmultipliers to provide a resultant phasor given by E cos ( omega mt+ phic) representative of magnitude and phase, and means to detect linearlythe absolute value of said resultant phasor E cos ( omega mt+ phi c).CM,2Verter as described in claim 1 further including means to measurethe magnitude of the output from said linear detector.
 3. A converter asdescribed in claim 2 further including a means to limit the amplitude ofsaid resultant phasor, E cos ( omega mt+ phi c), and means To comparethe phase of the signal output from said amplitude limiter to saidsignal from said reference source.
 4. A converter as described in claim3 wherein said means to compare phase consists of a 360* phase detector.